Generally, an aerosol valve comprises a hollow valve stem that has a valve actuator disposed atop the stem. The valve stem has a wider body portion at its base that is disposed within the aerosol container. The valve stem is disposed such that the valve stem emerges through a central opening in the pedestal portion of a mounting cup. Beneath the underside of the pedestal is a gasket which encircles a lateral orifice in the hollow valve stem and acts to seal the orifice in the valve stem when the valve is in a closed position. Beneath the gasket and clinched within the pedestal portion of the mounting cup is a valve housing; the valve housing surrounding the lower portion of the valve stem disposed within the container. A spring is disposed within the housing between the base of the housing and the valve body at the base of the valve stem. Extending below the housing is a hollow nipple for receiving a dip tube, which dip tube extends to the bottom of the container and functions as the conduit to deliver product/propellant to the interior of the housing. The valve is opened by either vertically depressing the valve stem to remove the gasket from the valve stem orifice and expose said orifice to the container contents or the valve stem is laterally moved, so-called tilt valve, to separate the gasket and the valve stem orifice and to thus expose the stem orifice to the container contents. Release of manual pressure on the valve stem causes the valve to return to its closed position; the spring functioning to press the valve body toward the gasket.
Metering valves are old in the aerosol industry. In the usual metering valve structure, product and propellant pass into the interior of the valve housing through a dip tube when the aerosol valve is in the closed position. During actuation or opening of the valve by manual pressure on the valve stem, valve structure is present that interrupts product/propellant flow from the dip tube to the interior of the housing. Thus, the discharge of product/propellant during the period that the valve is open will be limited to that amount of product/propellant present in the interior of the valve housing. When the manual pressure is released from the valve stem, the valve will close and the product/propellant will again flow into the interior of the valve housing. This closed/open cycle of the valve is repeated and each cycle will discharge a regulated amount of product/propellant. U.S. Pat. No. 3,658,214 ('214) is an example of a metering valve wherein flow from the dip tube to the interior of the housing is interrupted by having an upwardly extending tubular member situated in the valve housing pass in sealing contact with an opening on the base of the valve stem when the valve stem is depressed to a valve open position; the product/propellant passing through the dip tube being blocked from passing beyond the seal between tubular member and the opening in the base of the valve stem. Obviously, to create an effective seal according to the structure of the '214 patent demands a precise size tolerance between the sealing surfaces of the tubular member and the interior sealing surface of the opening in the base of the valve stem. In a massed-produced item such as an aerosol valve, this needed close tolerance is difficult to attain and maintain through the life of the use of the mold. Poor tolerance quality will result in a leak path for the product/propellant to the interior of the valve housing and consequent discharge when the valve is open (poor metering) or difficulty in actuating the valve to a valve open position where the tolerance error is an oversize in one or both sealing surfaces.
For certain applications, in particular, non-medical applications, the amount of product to be delivered by the aerosol metering valve is not critical, i.e., there can be a variation in the precise amount discharged upon actuation or opening of the valve and the metering valve still serves an important function. Thus, the aerosol industry has need of a valve which assuredly will seal off access to the dip tube during pressure filling of the container with propellant; for a metering valve that assuredly will shut off flow from the container into the interior of the valve housing when the valve is opened and for a valve having the structural capability of functioning as a metering valve or a continuous discharge valve; the ultimate functioning of the valve as a metering valve or a continuous valve being determined at the time of the initial actuation of the valve, i.e., at the time of propellant filling.
The subject invention accomplishes the aforementioned needs.